4.6 A NOTE ON SOME SANSKRIT MANUSCRIPTS ON ASTRONOMICAL INSTRUMENTS Yukio Ohashi (Visiting Scholar) Dept. of Mathematics, University of Lucknow, Lucknow, India. (Permanent address: 3-5-26 Hiroo,Shibuya-ku,Tokyo,Japan) INTRODUCTION The earliest astronomical instruments in India are the sarku (gnomon) and the gha%ika (clepsydra). The former is mentioned in the Sulbasutras, and the latter in the Vedafqajyotisa. Aryabhata described a rotating model of the celestial sphere. After Aryabhata, several instru­ ments were described by Varahamihira, Brahmagupta,Lalla, Srlpati, and Bhaskara II. After Bhaskara II, some Sanskrit texts specialized on astronomical instruments were composed. The earliest text of this kind is the Yantra-raja (AD 1370) written by Mahendra Suri. It is also the first text on the astrolabe in Sanskrit. After Mahendra Suri, Padmanabha, Cakradhara, Ganesa-Daivajna etc. composed Sanskrit texts on instruments, but most of them remain unpublished. YANTRA-KIRANAVALI OF PADMANABHA Padmanabha composed the Yantra-kirariavaU or Yantra- ratnavali (ca.AD 1400), of which Chapter II entitled Dhruvabhramaria- adhikara is well known1. The dhruvabhramana-yantra is a rectangular board with a slit to observe the "polar fish" (a group of stars around the North Pole) for finding time. The Tagore Library of Lucknow_University has a unique manuscript of its Chapter I, namely the Yantraraja-adhikara. 2 It consists of 11 6 verses and has a commentary, probably written by its author Padmanabha him­ self . It describes the construction and use of an astrolabe. Padmanabha takes the circumference of the instrument as the diurnal circle of the first point of Cancer, and draws the diurnal circles of the first points of Aries and Capricorn inside. It is opposite to the usual way. He writes: "A circular instrument, which is made of metal, constructed with any arbitrary radius by means of a pair of compasses (karkata, it also means Cancer), whose circumference is supported loosely, should be made. Then a horizontal and a vertical straight lines, passing through the centre, should be drawn. The upper half of the circumference should be graduated with degrees of three signs (90 ) on both sides. Two (horizontal) lines should be drawn on one-third-less forty one degrees(40 40') and twenty five and a twelfth degrees (25°5') (above the horizontal line passing through the centre)'.'1* Downloaded from https://www.cambridge.org/core. IP address: 170.106.35.229, on 29 Sep 2021 at 00:32:28, subject to the Cambridge Core terms of use, available at https://www.cambridge.org/core/terms. https://doi.org/10.1017/S0252921100106037 192 Ohashi: Sanskrit manuscripts on astronomical instruments "A pair of diurnal circles which are touching them (two horizontal lines) should be drawn. The intermediate space, between the diurnal circle of Capricorn and Aries, and also (between the circles of Aries and) the circumference, should be divided by degrees of obliquity of the ecliptic along the vertical line. Then the intermediate space between the centre and the circle of Capricorn which is the lowest circle should be divided into sixty six degrees. The sun indeed rotates along a certain circle which is called Cancer etc'.' The above mentioned values 40 40' and 25 5' show that the obliquity of the ecliptic6 was taken as about 23°50 ', although the value of the co-obliquity of the ecliptic is given as 66 in the next verse, and calculation is made by taking the obliquity of the ecliptic as 24° which is the common value in Hindu astronomy. The value £= 23 50' does not appear in the earlier Hindu works, but it is close to the Ptolemy's value7, e=23°51'20". On the contrary, Mahendra Suri8 used E=23°35' which is the same as al-Battani's value9. It seems that the measure of the instrument has been borrowed from certain Islamic source, which is different from the source of Mahendra Suri, but the theory of the instrument is explained in Hindu traditional manner. The author Padmanabha further continues to explain the method to draw the six o'clock line, prime vertical, altitude circles etc. quoting Sridhara, Brahmagupta and Bhaskara II in his commentary. He wrote that six instruments were described10, but only two adhikaras, which describe one instrument each, are now available. DIKSADHANA-YANTRA OF PADMANABHA The Oriental Institute of Baroda has a unique manuscript of the Diksadhana-yantra written by Padmanabha11. It consists of 1_8 verses. D.Pingree conjectured, that it is Chapter I of the Yantra-kiranavali or Yantra-ratnavali \2, butt it is wrong because the colophon of the Yantraraja-adhikara of the Tagore Library (Lucknow University) clearly states that it is Chapter I of the Yantra-kiranavali, hence the Diksadhana-yantra cannot be Chapter I of the Yantra-kiranavali. The manuscript of the Diksadhana-yantra does not mention the title Yantra- kiranavali nor the Yantra-ratnavali. The diksadhana-yantra is a wooden horizontal square board with a vertical 12 ahgula gnomon at its centre. A circle of radius 20 ahgulas is drawn at its centre, and concenteric circles are drawn inside at every ahgula. Then east-west and north-south lines, passing through the centre, are drawn. He gives the agra (radius of the circle into sine of amplitude) corresponding to the radius which is equal to the desired hypotenuse (the hypotenuse of a triangle whose base is the desired shadow and upright is the 12 ahgula gnomon) as follows! Downloaded from https://www.cambridge.org/core. IP address: 170.106.35.229, on 29 Sep 2021 at 00:32:28, subject to the Cambridge Core terms of use, available at https://www.cambridge.org/core/terms. https://doi.org/10.1017/S0252921100106037 Ohashi: Sanskrit manuscripts on astronomical instruments 193 . - Rsin <$ x palakarna x istakarna Agm ~ R x 12 where R is the radius of the celestial sphere, 6 is the declination of the sun, palakarna is the equinoctial midday hypotenuse (i.e. (12/cos<t>, where <j> is the terrestrial latitude), and istakarna is the desired hypotenuse. This agra means the difference between the length of the equinoctial midday shadow and the north-south projection (bhuja or base) of the desired shadow. He instructs to obtain east-west projection (koti or upright) of the shadow from the bhuja applying the Pythagorean theorem. He requires to find time using bhuja, but the method is not explicitly given. He also asks to draw the locus of the tip of the shadow. The locus is considered to be a circle which passes through the tip of the midday shadow and the tips of the shadows whose corresponding hypotenuse is 60 argulas in the morning and evening. He writes: "The north-south projection (bahu or bhuja) of the shadow and the east- west projection (koti ) of the shadow which are stated before should be determined from the 60 ahgula hypotenuse of shadow. The north-south projection should be diminished by the midday shadow. It is the arrow (versed sine). The koti is the desired sine. Determine the measure of the circle with the help of them and midday shadow. If the circle is drawn with that diameter, then the tip of the shadow of the desired gnomon will not leave its circumference on that day"1^ PRATODYA-YANTRA OF GANESA-DAIVAJNA Ganesa Daivajna (b. AD 1507) wrote the Pratoda-yantra15, which consists of 13 verses. It is a kind of sun-dial with a horizontal gnomon. Munisvara (b. AD 1603) described this instrument in his Siddhanta- sarvabhauma16 in 8 verses1! It has a commentary by Munisvara himself. The extract of this Munisvara's version was frequently copied. Munisvara calls it pratoda-yantra in the text18, but calls it cabuka-yantra in the commentrary. Hence the extract is sometimes entitled Cabuka-yantra19 and sometimes Pratoda-yantra20. In the case of the latter, the name of the instrument in the comentary was changed into pratoda-yantra. The Munisvara's version has been published21. Sometimes this Munisvara's version is wrongly stated as Ganesa's work. D.Pingree mentions a tika by Ganesa himself on the Pratoda-yantra22 but its existence is doubtful . CONCLUSION The history of astronomical instruments in India between Bhaskara II and Jai Singh Sawai is still unclear although there are several sources. The present paper is only a preliminary report of this subject on which I am now doing research. ACKNOWLEDGEMENTS I am thankful to Dr. K. S. Shukla, Retired Professor in Mathematics, Lucknow University, who is guiding my research. Downloaded from https://www.cambridge.org/core. IP address: 170.106.35.229, on 29 Sep 2021 at 00:32:28, subject to the Cambridge Core terms of use, available at https://www.cambridge.org/core/terms. https://doi.org/10.1017/S0252921100106037 194 Ohashi: Sanskrit manuscripts on astronomical instruments I am also grateful to the Directors and/or Librarians of the following Libraries who kindly allowed me to consult manuscripts (The abbrevia­ tions used in the notes are indicated within brackets). 1 Tagore Library, Lucknow University, Lucknow(Lucknow). 2 Sarasvati Bhavan, Sampurnanand Sanskrit Vishvavidyalaya, Varanasi (Benares). 3 Vishveshvaranand Vishva Bandhu Institute of Sanskrit and Indological Studies, Panjab University, Hoshiarpur (VVRI). 4 Scindia Oriental Research Instiute, Vikram University, Ujjain (SOI). 5 Oriental Institute, Baroda (Baroda). 6 The Asiatic Society of Bombay, Bombay (AS Bombay). REFERENCES AND NOTES 1 Dikshit,S.B. (1981). Bharatiya Jyotish Shastra, Part II. English tr. by R.V. Vaidya, p.231. India Meteorological Department. Garrett,A.ff.(1902). The Jaipur Observatory and its Builder, pp.62-63. Allahabad. I am grateful to the Librarian of BHU who supplied me its photocopy. There are several manus­ cripts of this adhikara. See Pingree,D.